The goal of the proposed research is to determine if cellular or chemical factors encountered during maturation affect the expression of neurochemical membrane receptors on astroglia. There is overwhelming evidence which demonstrates that astroglia isolated from immature brain and grown in culture exhibit a variety of receptor systems which respond to neurochemical messages. Recent studies reported from this laboratory suggest that there are at least two pharmacologically-distinct populations of astroglia which can be distinguished on the basis of their expresion of beta-adrenergic receptors. These results were obtained using a novel technique which enables us to examine receptors via receptor autoradiography on immunocytochemically-identified cells. Our system includes a microcomputer-based video image digitizer which enables us to quantify autoradiographic data. Using this approach, it will be possible to examine a number of important questions concerning the pharmacological properties of astrocytes which had not previously been approachable. The following three general questions will be addressed in this proposal. First, do astroglia continue to express membrane receptors following maturation in vitro or in vivo? Second, do immature astroglia or mature astrocytes vary in their expression of membrane receptors as a function of the brain region from which they are prepared? Third, do specific populations of neurons, identified immunocytochemically, affect the expression of astroglial membrane receptors? An examination of these questions should provide valuable information concerning the manner through which neurons and astrocytes communicate during normal and abnormal brain function.